Dual display system

ABSTRACT

A display system includes a base, a pair of electronic displays, and an arm assembly that supports the displays from the base in vertical or horizontal registration. In one implementation, the arm assembly is a single telescopic member that rotates relative to the base and locks in vertical and horizontal orientations, the displays rotate relative to the member between corresponding extreme angular positions in which the operative angular orientation of the displays relative to horizontal is maintained, and the length of the member is adjusted to minimize separation of the displays. In another implementation, the arm assembly has separate arms rotating about vertically spaced axes and linked to minimize the separation of the displays automatically when vertically or horizontally registered. In a simple implementation, the arm assembly is a rigid arm that releasably attaches to the base only in vertical and horizontal orientations, the displays mounted releasably to the arm in pre-defined angular orientations that preserve their operative angular orientation, and one display can be connected to the arm at spaced apart position to adjust separation of the displays.

FIELD OF THE INVENTION

The invention relates generally to electronic displays used withcomputers, and more particularly, to a display system permittingconvenient positioning of dual displays.

BACKGROUND OF THE INVENTION

Computers are readily adapted to operate multiple displays. Pairedmonitors are useful when large amounts of related information, such asdata or graphics, must be compared. Paired monitors can be inconvenient,however, where limited desk space is available. Also, in some instancesinformation may be best presented with the monitors horizontallyaligned, and in other instances, with the monitors vertically aligned.Conventional practices do not permit such selection or changing ofmonitor orientations.

SUMMARY OF THE INVENTION

In one aspect, the invention provides a display system comprising abase, a pair of electronic displays, and means for positioning thedisplays selectively in vertically registered relationship and inhorizontally registered relationship. The positioning means comprise anarm assembly which supports the displays and which may comprise a singlerotary arm, a pair of arms rotating about separate axes, a single armlocatable in two desired orientation or interchangeable arms ofdifferent length. The positioning means support the arm assembly fromthe base selectively in a first orientation relative to the base inwhich the displays are positioned in vertically registered relationshipand in a second orientation in which the displays are positioned in ahorizontally registered relationship. Each display has an operativeangular orientation relative to horizontal (neglecting tilting which isnormally permitted about a horizontal or vertical axis). For example, alandscape display is normally operated with its lengthwise axis orientedhorizontal as the video board operating the display will normally aligntext or other displayed matter with the display's lengthwise axis. Thepositioning means thus include means for adjusting the angularorientation of each of the displays relative to the arm assembly toorient each display in its operative angular orientation when the armassembly is in either of its orientations with the displays eithervertically or horizontally registered.

In one implementation of the invention, the arm assembly rotates about agenerally horizontal axis relative to the base, and each display rotatesrelative to the arm assembly. The arm assembly may be releasably lockedin either of its pair of orientations, typically vertical or horizontal,and each display is permitted to rotate only between a pair of extremeangular positions relative to the arm assembly. Each extreme angularpositions corresponds to a different orientation of the arm assemblyrelative to the base so that each display is oriented in its operativeangular orientation whenever the arm assembly is locked to the base ineither of the orientations and the display is rotated to itscorresponding angular position. In another implementation, the armassembly and the displays are coupled so that the angular orientation ofeach display relative to the arm assembly changes as the arm assemblydisplaces between its pair of orientations, ensuring that each displayautomatically orients in its operative angular orientation whenever thedisplays are vertically or horizontally registered.

The displays will often be horizontally elongate in their operativeangular orientation. It will generally be desirable to minimize thespacing between edges of the displays whether vertically registered orhorizontally registered. To that end, the center-to-center spacingbetween the displays is preferably reduced when the displaces arevertically registered and increased when the displays are horizontallyregistered. In one approach, the arm assembly may be a telescopic memberthat permits telescopic adjustment of display spacing. In anotherapproach, one display may mounted to the arm assembly in differentpositions spaced apart along the arm. In a particularly robustarrangement, the one display has a plug that interlocks with either of apair of sockets located proximate to one end of the arm assembly andspaced apart axially along the arm assembly.

In yet another implementation, the spacing between horizontally elongatedisplays is automatically adjusted as the arm assembly is displacedbetween orientations that place the displays in horizontal and verticalregistration. The arm assembly comprises a pair of horizontally spacedapart arms rotating in parallel planes. Means supporting the armassembly from the base comprise upper and lower rotary shafts inparallel relationship. One arm has its fixed end fixed to the uppershaft such that the arm rotates in a plane perpendicular to the uppershaft. The other arm has a fixed end fixed to the lower shaft such thatthe other arm rotates in a plane perpendicular to the lower shaft inresponse to rotation of the upper shaft. In their vertically registeredrelationship, a predetermined one of the displays is located below theother display. The one display (lower when vertically registered) ismounted to the free end of the one arm fixed to the upper shaft, and theother display (upper when vertically registered) is mounted to the freeend of the other arm fixed to the lower shaft. Since one arm extendsdownwardly to support the lower display and the other arm extendsupwardly to support the upper display, the center-to-center spacingbetween the displays is effectively reduced when registered. However,when the arms are rotated outwardly to position the displays inhorizontal registration, the center-to-center spacing increases.

Various aspects of the invention will be apparent from a descriptionbelow of a preferred embodiment and will be more specifically defined inthe appended claims.

DESCRIPTION OF THE DRAWINGS

The invention will be better understood with reference to drawings inwhich:

FIGS. 1-6 illustrate a first display system with dual displays invarious orientations;

FIG. 7 is a partially exploded, fragmented perspective view detailingthe mounting of an arm to a base of the display system;

FIGS. 8 and 9 are exploded perspective views detailing how one displayis mounted to the arm with a novel ball and socket joint;

FIGS. 10 and 11 fragmented elevational views, partially cross-sectioned,illustrating how rotation of one display relative to the arm isrestricted to a 90 degree range between two well-defined positions;

FIG. 12 is a rear elevation, partially sectioned, showing a seconddisplay system in which dual displays rotate in response to rotation ofan arm assembly about a base;

FIG. 13 is a plan view of the second display system from above showinglinkage coupling the/arm and displays;

FIGS. 14-16 are front elevations showing different relative orientationsof the displays of the second system;

FIG. 17 is a side elevation showing a third display system with an armvertical and supporting dual displays in vertical registration;

FIG. 18 is a plan view from above showing the third display system withthe arm horizontal and supporting the display in horizontalregistration;

FIG. 19 is an exploded perspective view, extensively fragmented,detailing how the arm mounts to a base and how the displays mount to thearm; and,

FIG. 20 is a perspective view of the a ball and socket joint used tomount one of the displays of the third display system.

DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is made to FIGS. 1-6 which illustrate a first display system10 which includes a base 12 configured to stand on a horizontal surfaceand a pair of landscape displays 14, 16 (preferably liquid crystaldisplays). The displays 14, 16 are mounted to opposing ends of atelescopic arm 18, and a hollow upright 20 associated with the base 12supports the arm 18 for rotation. Each display 14 or 16 has aconventional port 22 permitting coupling to a computer (not illustrated)through a conventional video board (not illustrated).

A rotary joint (detailed in the exploded view of FIG. 7) couples the arm18 to the upright 20. The rotary joint is configured to perform twofunctions: to support the arm 18 for rotation about a generallyhorizontal axis 26 through the upright 20, and to define distinctvertical and horizontal arm positions. The rotary joint includes aconnector 28 fixed centrally to the rear of the arm 18, which includes acircular track 30 and a generally circular central projection 32. Theupright 20 carries a complementary connecting structure comprising acircular recess 34 that receives the projection 32, a washer 36, and abolt 38 that fastens to the projection 32. The washer 36 extendsradially beyond the circular recess 34 and abuts the inner surface ofthe upright 20 to retain the projection, and rotates with the projectionabout the generally horizontal axis 26.

A detent mechanism releasably locks the arm 18 in vertical andhorizontal positions. Two indentations 40, 42 are formed in the circulartrack 30 at positions spaced circumferentially by 90 degrees. Acylindrical recess 44 in the upright 20 contains a ball 46 and a biasingspring 48 that urges the ball 46 against the track 30. The ball 46 seatsin either indentation 40 or 42 to lock the arm 18 in its vertical orhorizontal position but releases from either indentation 40 or 42 inresponse to manual rotation of the arm 18.

Mounting structure 50 that mounts one display 16 to the arm 18 isdetailed in FIGS. 8-11. The mounting structure 50 is configured toperform two principal functions: to permit limited tilting of thedisplay 16 about two mutually perpendicular axes, and to allow rotationof the display 16 relative to the arm 18 through a limited angle betweentwo well-defined positions. The mounting structure 52 coupling the otherdisplay 14 to the arm 18 is substantially identical and will not bedescribed.

The mounting structure 50 includes a ball joint comprising a steel ball56 formed on a steel shaft 58 supported from the arm 18 and a plasticsocket 60 supported from the rear of the display 16. The socket 60 isformed with four slots that are oriented parallel to the socket'sreceiving axis and appearing generally horizontal in the operativeorientation of the socket 60. One pair of slots 62 is verticallyregistered, and another pair of slots 64 is horizontally registered. Theball 56 carries four cylindrical projections oriented in a common plane.One pair of projections 66 are aligned with a vertical axis (not shown)and extend from the ball 56 in opposite axial directions. Another pairof projections 68 are aligned with a horizontal axis (not shown) andextend from the ball 56 in opposite axial directions. The verticalprojections 66 are received in the vertically registered slots 62,permitting free rotation of the display 16 about the vertical axis, butonly limited rotation of the display 16 about the horizontal axis. Thehorizontal projections 68 are received in the horizontally registeredslots 64, permitting free rotation of the display 16 about thehorizontal axis, but only limited rotation of the display 16 about thevertical axis. This arrangement effectively permits only limited degreeof tilting of the display 16 about two mutually perpendicular axes, inthis implementation about vertical and horizontal axes. It should benoted that the slots might be formed on the exterior of the ball 56, andthe projections might be fixed to the socket 60 and extend inwardly toengage the slots. The arrangement illustrated, in which the projections66, 68 are fixed to the ball 56 and the slots 62, 64 are formed in thesocket 60, permits easy manufacture and assembly. The slots 62, 64extend rearward from the display 16 and terminate open-ended,facilitating insertion of the projections 66, 68 into the slots 62, 64as the socket 60 receives the ball 56.

The shaft 58 is mounted for rotation relative to the arm 18 about arotational axis 70 parallel to the generally horizontal axis 26 aboutwhich the arm 18 rotates. The arm 18 has a clearance hole 72 in itsforward surface surrounded by a circular seating surface 74, and acylindrical socket 76 within the arm 18 that is aligned with therotational axis 70 and the clearance hole 72. The shaft 58 has anannular flange 78 that presses a split washer 79 against the circularseating surface 74 as the shaft 58 is inserted centrally through theclearance hole 72 into the socket 76. The shaft 58 has three projectionsor tabs oriented in a common plane and extending radially from the shaft58. One pair of tabs 80 is closely spaced and a single tab 82 ispositioned diametrically opposite the pair of tabs 80. The clearancehole 72 is configured to receive the tabs 80, 82 in a particular angularorientation as the shaft 58 is inserted into the socket 76, and rotationof the tabs 80, 82 from that particular angular orientation preventsremoval of the shaft 58 from the arm 18. The tabs 80, 82 also functionas stop structures cooperating with stop structures in the arm 18 torestrict rotation of the display 16, as explained below.

Rotation of the shaft 58 is restricted by two stops: a rotatable stop 84that threads into a socket 88 within the arm 18 (complementary threadsnot shown), and a generally triangular fixed stop 90 formed on an innersurface of the arm 18. The rotatable stop 84 has a hexagonal key slot 92to permit rotation of the stop 84 between a clearance position shown inFIG. 10 and an operative position shown in FIG. 11 in which the stop 84engages an abutment molded with the cylindrical socket 76. Afterinsertion into the socket 76, the shaft 58 is manually rotated clockwiseuntil the single tab 82 passes the stop 84, for example, to one extremeangular position in which the single tab 82 abuts the fixed stop 90 asin FIG. 10. The rotatable stop 84 can then be placed in its operativeposition as shown in FIG. 11. When the shaft 58 is then rotatedcounterclockwise, the single tab 82 engages the rotatable stop 84 asshown in FIG. 11. Rotation of the shaft 58 and thus the display 16relative to the arm 18 is restricted to 90 degrees between two extremeangular positions well-defined by the stops.

The two well-defined positions of the display 16 relative to the arm 18correspond to the two well-defined positions of the arm 18 relative tothe base 12. The display 16 position (relative to the arm 18) defined inFIG. 11 corresponds to the horizontal orientation of the arm 18 andpreserves the landscape orientation of the display 16. The overallarrangement is apparent in FIGS. 3 and 4 where the arm 18 is horizontaland the displays 14, 16 are oriented in horizontally side-by-siderelationship with their lengthwise axes (not illustrated) in an absolutehorizontal orientation. The display 16 position (relative to the arm 18)defined in FIG. 10 corresponds to the vertical orientation of the arm 18and once again preserves the landscape orientation of the display 16.The overall arrangement is apparent in FIGS. 5 and 6 where the arm 18 isvertical and the displays 14, 16 are vertically registered. Thetelescopic arm 18 is extended in its horizontal orientation to increasethe spacing between the displays 14, 16, and contracted in its verticalorientation to decrease the spacing between the displays 14, 16,effectively accommodating the horizontal elongation of the displays 14,16. A conventional detent mechanism may be mounted in the arm 18 to fixits different vertical and horizontal lengths.

Reference is made to FIGS. 12 and 13 which illustrate a second displaysystem 100 comprising a base 102, an arm assembly 104 that rotates abouta generally horizontal axis from an upright 105 associated with the base102, and a pair of landscape displays 106, 108 mounted to opposing endsof the arm assembly 104. The arms 110, 112 have not been shown in FIG.12 to better illustrate linkage rotating the displays 106, 108 with thearm assembly 104.

The arm assembly 104 comprises a pair of distinct arms 110, 112(apparent in FIG. 13), one arm 110 in front of the upright 105 and theother arm 112 behind the upright 105. The upright 105 supports a centralshaft 114 for rotation about a generally horizontal central axis and acentral toothed gear 116 is fixed to the central shaft 114. The arms110, 112 are fixed to parallel rotary shafts 118, 120 mounted forrotation to the upright 105 about their lengthwise horizontal axes, onerotary shaft 118 above the central shaft 114 and the other rotary shaft120 below the central shaft 114. Each arm 110 or 112 has a fixed endfixed to its respective rotary shaft 118 or 120 such that each rotatesin a plane perpendicular to the lengthwise axis of the associated shaft118 or 112, the two arms 110, 112 being horizontally spaced to avoidcontact during such rotation. The upper and lower rotary shafts 118, 120carry toothed part-circular gears 122, 124 (spanning 90 degree sectors)that are meshed with the circular central gear 116. The central shaft114 and the meshed gears 116, 122, 124 constrain the upper and lowerrotary shafts 118, 120 to rotate together in the same angular direction.Although not apparent, end teeth of the upper and lower part-circulargears 122, 124 are shaped to limit rotation of the gears 122, 124relative to the central gear 116.

One display 106 is mounted with a ball joint 126 to a horizontal shaft128, and the shaft 128 is mounted for rotation about its centralhorizontal axis to a free end of the rear arm 112. The ball joint 126 ispreferably configured with pins and slots like the ball joint describedabove, to provide limited tilting of the display 106, but such aconfiguration has not been illustrated in FIG. 13. The rotary shafts120, 128 associated with the rear arm 112 are coupled with a toothedbelt 130 running on pulleys fixed to the shafts so that the display 106rotates in response to rotation of the rotary shaft 120 and thus rotatesrelative to the rear arm 112. The other display 108 is mounted with asimilar ball joint 132 to a shorter horizontal shaft 134, and theshorter shaft 134 is mounted for rotation about its horizontal centralaxis to the free end of the forward arm 110. The rotary shafts 118, 134associated with the forward arm 110 are similarly coupled with a toothedbelt 136 to coordinate rotation of the other display 108 in response torotation of the rotary shaft 118 and thus rotates relative to theforward arm 110.

Various orientations of the second display system 100 are shown in FIGS.14-16. The "diagonal" orientation of the two displays 106, 108 in FIG.14 corresponds to the orientation of the arm assembly 104 and variousgears in FIGS. 12 and 13. This is an intermediate orientation from whichthe arm assembly 104 can be rotated through about 45 degreescounterclockwise to achieve the vertically spaced orientation of thedisplays 106, 108 in FIG. 15 or about 45 degree clockwise to achieve thehorizontally side-by-side orientation of the displays 106, 108 shown inFIG. 16. The arm assembly 104 is effectively coupled to each of thedisplays 106, 108 so that the absolute landscape orientation of the twodisplays 106, 108 is, for practical purposes, maintained as the armassembly 104 rotates. In this embodiment, the displays 106, 108 must betitled to orient one effectively behind the other to allow rotation ofthe arm assembly 104. This can be avoided by lengthening the arms 110,112 to increase the separation of the displays 106, 108.

The center-to-center spacing between the displays 106, 108 isautomatically adjusted when the displays 106, 108 are placed in verticalor horizontal registration. When vertically registered, one display 108is always located below the other display 106. From examination of FIG.12, it will be apparent that the lower display 108 would then besupported by the arm 110 extending downward from the upper rotary shaft120, and the upper display 106 would be supported with the arm 112extending upward from the lower rotary shaft 118. The arms 110, 112 thenoverlap for a large portion of their length and the distance betweentheir free ends and thus the centers of the displays 106, 108 isminimized. From the orientation of FIG. 12, to place the displays inhorizontal registration, the arms 110 would swing upward and outward toone side of the upright 105 and the arm 112 would swing downward andoutward on an opposing side of the upright 105, increasing theseparation of their free ends and thus the center-to-center spacing ofthe displays 106, 108.

The automatic adjusting of the orientation of the displays 106, 108 canbe implemented with a simpler arm assembly comprising just a single armcentrally mounted to a supporting base on a central rotary shaft. Beltsor other linkages can be used to couple the central rotary shaft torotary shafts supporting the displays 106, 108 to opposing ends of thesingle arm. However, use of two arms 110, 112 pivoting about separateaxes permits simultaneous adjustment of display spacing.

Reference is made to FIGS. 17 and 18 which illustrate a third displaysystem 150 which includes a pair of landscape displays 152, 154 and abase 156 with an upright 158. The third display system 150 uses an arm162 that mounts to the upright 158 in only two orientations. In FIG. 17,the arm 162 is mounted to the upright 158 in a vertical orientation, andthe displays 152, 154 are mounted to opposing ends of the arm 162 with apair of identical connectors 164, 166. In FIG. 18, the arm 162 ismounted to the upright 158 in a horizontal orientation, and the displays152, 154 are mounted to opposing ends of the longer arm 162 using thesame connectors 164, 166. In each instance, the lengthwise axes of thedisplays 153, 154 are kept horizontal.

The connector 164 associated with one display 152 is shown in FIG. 20.The connector 164 includes a ball joint comprising a molded plasticsocket 170 and an aluminum ball 172 formed with a shaft 174. The socket170 is formed with slots 178 and the ball 172 is formed with projections180, comparable to those above, which interlock to permit only limitedtilting of the display 152 along two mutually perpendicular axes. Apress is used to insert the ball 172 into the socket 170, and a housingcomprising a plate 182 and a shell 184 closely conforming to theexterior of the socket 170 is mounted with screws 186 around theassembled ball 172 and socket 170. The plate 182 is then fastened withscrews (such as the screw 188) to the back of the display 152. A flat190 formed at the top of the socket 170 seats against a correspondingflat 192 in the shell 184 to prevent rotation of the socket 170 relativeto the display 152. The shaft 174 is terminated with a plug 194 with atapering square transverse cross-section and with a central threadedhole 196. As apparent in FIG. 19, the arm 162 has a connector,specifically, a socket 198 which conforms in shape to and interlockswith the plug 194 to support the display 152 and to prevent rotation ofthe display 152. The socket 198 is arranged on the arm 162 to receivethe plug 194 in two distinct relative angular orientations spaced by 90degrees, one in which the lengthwise axis of the display 152 is alignedwith the length of the arm 162 (as in FIG. 18 where the arm 162 ishorizontal) and another in which the lengthwise axis is perpendicular tothe length of the arm 162 (as in FIG. 17 where the arm 162 is vertical).A bolt 200 (shown in FIG. 19) inserts through the socket 198 into theplug 194 to prevent separation.

The other display 154 is mounted to the arm 162 in a manner permittingadjustment of the spacing between the displays 152, 154. The connector166 associated with the other display 154 is identical to the connector164. The arm 162 has a pair of sockets 202, 204 identical to the socket198 but mounted in an opposing end portion of the arm 162. The twosockets 202, 204 are axially spaced along the arm 162, one socket 204located substantially at one end of the arm 162 and the other socket202, inset from that end. Both sockets 202, 204 are shaped to interlockwith the connector 166 to prevent relative rotation and to permit thelengthwise axis of the display 154 to be aligned with or orientedperpendicular to the length of the arm 162 according to whether the arm162 is horizontally or vertically oriented.

The connectors used to join the arm 162 to the upright 158 are apparentin FIG. 19. The upright 158 has a socket 206 with a tapered squarechamber aligned with a circular cylindrical chamber. The arm 162 carriesa plug 208 which has a tapered square section and a circular cylindricalsection, conforming to the socket 206. The socket 206 receives the plug208 in two distinct relative angular orientations spaced by 90 degrees,which correspond to vertical and horizontal orientations of the arm 162.A bolt 210 inserts through a clearance hole (not illustrated) in therear of the socket 206 and threads into the plug 208 to prevent relativeaxial separation of the socket 206 and plug 208.

How the display system 150 is used will be largely apparent from theforegoing description of its components. If the displays 152, 154 are tobe horizontally registered (as in FIG. 18), the arm 162 is mounted tothe upright 158 in a horizontal position, and the displays 152, 154 aremounted to the arm 162 with their lengthwise axes aligned with thelength of the arm 162. The display 152 is mounted to the socket 204 atthe end of the arm 162 to increase the spacing between the displays,accommodating their horizontal elongation. If the displays 152, 154 areto be vertically registered (as in FIG. 17), the arm 162 is mounted tothe upright 158 in a vertical position, and the displays 152, 154 aremounted to the arm 162 with their lengthwise axes perpendicular to thelength of the arm 162. The spacing between the displays 152, 154 isreduced by mounting the display 152 is mounted to the socket 202 insetfrom the end of the arm 162.

The display 152 may be mounted appropriate connection means that permitthe display 152 for sliding between various axially spaced-apartpositions along the arm 162. However, twin sockets 202, 204 are simple,adequate and comparatively inexpensive. Another alternative is toprovide an arm assembly comprising two interchangeable arms of differentlength. Each arm may carry a pair of sockets (substantially identical tothe socket 198) for mounting of the displays 152, 154 at opposing endsof the arm. Each arm may be fitted with a connector comparable to theplug 208 for mounting to the upright 158. The short armer may be mountedto the upright 158 in a vertical position for vertical registration ofthe displays 152, 154, and the longer arm may be mounted to the upright158 in a horizontal orientation for mounting for horizontal registrationof the displays 152, 154.

It will be appreciated that particular embodiments of the invention havebeen described and that modifications may be made therein withoutdeparting from the spirit of the invention or necessarily departing fromthe scope of the appended claims.

I claim:
 1. A display system comprising:a base; a pair of electronicdisplays, each of the displays having an operative angular orientationrelative to horizontal; positioning means for positioning the displaysselectively in vertically registered relationship and in horizontallyregistered relationship, the positioning means comprising:(a) an armassembly supporting the displays; (b) support means for supporting thearm assembly from the base selectively in a first orientation relativeto the base in which the displays are in their vertically registeredrelationship and in a second orientation in which the displays are intheir horizontally registered relationship; and, (c) mounting means formounting the displays to the arm assembly, the mounting means comprisingmeans for adjusting the angular orientation of each of the displaysrelative to the arm assembly thereby to orient each of the displays inits operative angular orientation when the arm assembly is in either oneof its first and second orientations.
 2. The display system of claim 1in which:the support means support the arm assembly for rotation about agenerally horizontal axis; and, the mounting means mount each of thedisplays to the arm assembly for relative rotation about a rotationalaxis substantially parallel to the generally horizontal axis.
 3. Thedisplay system of claim 2 in which:the support means comprise means forreleasably locking the arm assembly to the base in its first and secondorientations; and, the mounting means comprise means permitting rotationof each of the electronic displays only between a pair of extremeangular positions relative to the arm assembly, each of the angularpositions corresponding to a different one of the first and secondorientations of the arm assembly such that the display is oriented inits operative angular orientation whenever the arm assembly is locked tothe base in either of the first and second positions and the display isrotated to its corresponding angular position.
 4. The display system ofclaim 3 in which the mounting means comprise:a shaft fixed to one of thedisplays and aligned with the rotational axis of the one display; meansfixed to the arm assembly and supporting the shaft for rotation aboutthe rotational axis of the one display; and, complementary stopstructures fixed to the shaft and to the arm assembly and positioned toengage as the shaft rotates relative to the arm assembly.
 5. The displaysystem of claim 2 in which:the support means permit displacement of thearm assembly on the base between the first and second orientations; and,the means for adjusting the angular orientation of the displays comprisemeans supporting each of the displays for rotation relative to the armassembly and means coupling each of the displays to the arm assembly forrotation in response to displacement of the arm assembly between thefirst and second orientations.
 6. The display system of claim 1 inwhich:each of the displays is horizontally elongate in its operativeangular orientation; and, the arm assembly is an elongate telescopicmember and the displays are mounted to opposing ends of the arm assemblysuch that the spacing of the displays in their horizontally andvertically registered relationships can be adjusted.
 7. The displaysystem of claim 1 in which the mounting means are adapted to permittilting of one of the displays about a pair of mutually perpendicularaxes, the mounting means comprising:a ball supported from one of thedisplay and the arm assembly; a socket supported from the other of thedisplay and the arm assembly and containing the ball; a multiplicity ofprojections fixed to one of the ball and the socket, the multiplicity ofprojections comprising one pair of projections extending in oppositedirections along one of the mutually perpendicular axes and another pairof projections extending in opposite directions along the other of themutually perpendicular axes; and, a multiplicity of slots formed in theother of the ball and the socket, the multiplicity of slots comprising apair of opposing slots each of which receives a different one of the onepair of projections and another pair of opposing slots each of whichreceives a different one of the other pair of projections.
 8. Thedisplay system of claim 7 in which the projections are fixed to the balland the slots are formed in the socket.
 9. The display system of claim 1in which:each of the displays is horizontally elongate in its operativeangular orientation; a predetermined one of the displays is below theother of the displays in their vertically registered relationship; thesupport means comprise upper and lower rotary shafts in parallelrelationship and means mounting the shafts to the base for rotationabout their respective lengthwise axes; the arm assembly comprises apair of horizontally spaced-apart arms, each of the arms has a fixed endand a free end, one of the arms has its fixed end fixed to the uppershaft such that the one arm rotates in a plane perpendicular to theupper shaft in response to rotation of the upper shaft, the other of thearms has its fixed end fixed to the lower shaft such that the other armrotates in a plane perpendicular to the lower shaft in response torotation of the upper shaft; and, the one display is mounted to the freeend of the one arm and the other display is mounted to the free end ofthe other arm.
 10. The display system of claim 9 comprising constrainingmeans constraining the rotary shafts to rotate together in oppositeangular directions.
 11. The display system of claim 10 in which themeans for adjusting the angular orientation of the displayscomprise:means supporting each of the displays for rotation about agenerally horizontal rotational axis relative to the arm to which thedisplay is mounted; and, coupling means coupling the one display to theupper shaft and the other display to the lower shaft such that thedisplays rotate in response to rotation of the rotary shafts.
 12. Thedisplay system of claim 11 in which:the constraining means comprise anupper gear fixed to the upper shaft, a lower gear fixed to the lowershaft, a central rotary shaft mounted for rotation to the base betweenthe upper and lower shafts, and a gear fixed to the central rotary shaftand meshed with the upper and lower gears; the means supporting each ofthe displays for rotation comprise a pair of rotary shafts each mountedfor rotation to a different one of the arms and each supporting adifferent one of the displays; and, the coupling means comprise a pairof belts, each of the belts couples a different one of the pair ofrotary shafts supporting the displays to a different one of the upperand lower rotary shafts.
 13. The display system of claim 1 in which:eachof the displays is elongate along a horizontal axis of the display whenoriented in its operative angular orientation; the arm assemblycomprises an elongate arm; and, the mounting means comprise connectormeans for connecting one of the displays to the arm at positions spacedalong the arm, whereby, the spacing between the displays can beadjusted.
 14. The display system of claim 13 in which the connectormeans for connecting the one display to the arm comprise:a first socketmounted to the arm proximate to one end thereof; a plug mounted to theone display and shaped to interlock with the socket to prevent rotationof the plug relative to the socket, the socket being shaped to receivethe plug in either of a pair of orientations that are rotatedsubstantially by 90 degrees, the socket being positioned on the arm suchthat the horizontal axis of the one display is aligned with the lengthof the arm when the plug is in one of the orientations and thehorizontal axis of the one display is perpendicular to the length of thearm in the other of the relative angular positions; and, a second plugsocket mounted to the arm proximate to the one end thereof andsubstantially identical to the first plug, the first and second plugsbeing spaced apart along the arm.
 15. The display system of claim 14 inwhich the support means comprise:a plug fixed to the arm; and, a socketfixed to the base and shaped to interlock with the plug fixed to the armwhen the arm is in a vertical orientation and when the arm is in ahorizontal orientation, the plug fixed to the arm and the socket fixedto the base being shaped to prevent rotation of the arm relative to thebase when interlocked. .Iadd.
 16. A display system comprising:a basemember; a pair of electronic displays; positioning means for positioningthe displays, the positioning means comprising:(a) an arm assembly forsupporting the displays; (b) support means for supporting the armassembly from the base member; and (c) mounting means for mounting thedisplays to the arm assembly, the mounting means comprising means foradjusting the angular orientation of each of the displays relative tothe arm assembly to thereby permit said displays to be angled towardeach other to a desired degree..Iaddend..Iadd.
 17. A display systemcomprising:a pair of electronic displays; positioning means forpositioning the displays, the positioning means comprising:(a) an armassembly for supporting the displays; (b) support means having a basefor supporting the arm assembly above a support surface; and (c)mounting means for mounting the displays to the arm assembly, themounting means comprising means for adjusting the angular orientation ofeach of the displays relative to the arm assembly about a generallyvertical axis to thereby permit said displays to be angled relative toeach other to a desired degree..Iaddend.